Re: [RFC PATCH v10 2/5] iommu/vt-d: break out ATS Invalidation if target device is gone

Baolu Lu
2024-01-10T05:22:32Z

On 12/29/23 1:02 AM, Ethan Zhao wrote:
> For those endpoint devices connect to system via hotplug capable ports,
> users could request a warm reset to the device by flapping device's link
> through setting the slot's link control register, as pciehp_ist() DLLSC
> interrupt sequence response, pciehp will unload the device driver and
> then power it off. thus cause an IOMMU device-TLB invalidation (Intel
> VT-d spec, or ATS Invalidation in PCIe spec r6.1) request for device to
> be sent and a long time completion/timeout waiting in interrupt context.
>
> That would cause following continuous hard lockup warning and system hang
>
> [ 4211.433662] pcieport 0000:17:01.0: pciehp: Slot(108): Link Down
> [ 4211.433664] pcieport 0000:17:01.0: pciehp: Slot(108): Card not present
> [ 4223.822591] NMI watchdog: Watchdog detected hard LOCKUP on cpu 144
> [ 4223.822622] CPU: 144 PID: 1422 Comm: irq/57-pciehp Kdump: loaded Tainted: G S
> OE kernel version xxxx
> [ 4223.822623] Hardware name: vendorname xxxx 666-106,
> BIOS 01.01.02.03.01 05/15/2023
> [ 4223.822623] RIP: 0010:qi_submit_sync+0x2c0/0x490
> [ 4223.822624] Code: 48 be 00 00 00 00 00 08 00 00 49 85 74 24 20 0f 95 c1 48 8b
> 57 10 83 c1 04 83 3c 1a 03 0f 84 a2 01 00 00 49 8b 04 24 8b 70 34 <40> f6 c6 1
> 0 74 17 49 8b 04 24 8b 80 80 00 00 00 89 c2 d3 fa 41 39
> [ 4223.822624] RSP: 0018:ffffc4f074f0bbb8 EFLAGS: 00000093
> [ 4223.822625] RAX: ffffc4f040059000 RBX: 0000000000000014 RCX: 0000000000000005
> [ 4223.822625] RDX: ffff9f3841315800 RSI: 0000000000000000 RDI: ffff9f38401a8340
> [ 4223.822625] RBP: ffff9f38401a8340 R08: ffffc4f074f0bc00 R09: 0000000000000000
> [ 4223.822626] R10: 0000000000000010 R11: 0000000000000018 R12: ffff9f384005e200
> [ 4223.822626] R13: 0000000000000004 R14: 0000000000000046 R15: 0000000000000004
> [ 4223.822626] FS: 0000000000000000(0000) GS:ffffa237ae400000(0000)
> knlGS:0000000000000000
> [ 4223.822627] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 4223.822627] CR2: 00007ffe86515d80 CR3: 000002fd3000a001 CR4: 0000000000770ee0
> [ 4223.822627] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 4223.822628] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
> [ 4223.822628] PKRU: 55555554
> [ 4223.822628] Call Trace:
> [ 4223.822628] qi_flush_dev_iotlb+0xb1/0xd0
> [ 4223.822628] __dmar_remove_one_dev_info+0x224/0x250
> [ 4223.822629] dmar_remove_one_dev_info+0x3e/0x50
> [ 4223.822629] intel_iommu_release_device+0x1f/0x30
> [ 4223.822629] iommu_release_device+0x33/0x60
> [ 4223.822629] iommu_bus_notifier+0x7f/0x90
> [ 4223.822630] blocking_notifier_call_chain+0x60/0x90
> [ 4223.822630] device_del+0x2e5/0x420
> [ 4223.822630] pci_remove_bus_device+0x70/0x110
> [ 4223.822630] pciehp_unconfigure_device+0x7c/0x130
> [ 4223.822631] pciehp_disable_slot+0x6b/0x100
> [ 4223.822631] pciehp_handle_presence_or_link_change+0xd8/0x320
> [ 4223.822631] pciehp_ist+0x176/0x180
> [ 4223.822631] ? irq_finalize_oneshot.part.50+0x110/0x110
> [ 4223.822632] irq_thread_fn+0x19/0x50
> [ 4223.822632] irq_thread+0x104/0x190
> [ 4223.822632] ? irq_forced_thread_fn+0x90/0x90
> [ 4223.822632] ? irq_thread_check_affinity+0xe0/0xe0
> [ 4223.822633] kthread+0x114/0x130
> [ 4223.822633] ? __kthread_cancel_work+0x40/0x40
> [ 4223.822633] ret_from_fork+0x1f/0x30
> [ 4223.822633] Kernel panic - not syncing: Hard LOCKUP
> [ 4223.822634] CPU: 144 PID: 1422 Comm: irq/57-pciehp Kdump: loaded Tainted: G S
> OE kernel version xxxx
> [ 4223.822634] Hardware name: vendorname xxxx 666-106,
> BIOS 01.01.02.03.01 05/15/2023
> [ 4223.822634] Call Trace:
> [ 4223.822634] <NMI>
> [ 4223.822635] dump_stack+0x6d/0x88
> [ 4223.822635] panic+0x101/0x2d0
> [ 4223.822635] ? ret_from_fork+0x11/0x30
> [ 4223.822635] nmi_panic.cold.14+0xc/0xc
> [ 4223.822636] watchdog_overflow_callback.cold.8+0x6d/0x81
> [ 4223.822636] __perf_event_overflow+0x4f/0xf0
> [ 4223.822636] handle_pmi_common+0x1ef/0x290
> [ 4223.822636] ? __set_pte_vaddr+0x28/0x40
> [ 4223.822637] ? flush_tlb_one_kernel+0xa/0x20
> [ 4223.822637] ? __native_set_fixmap+0x24/0x30
> [ 4223.822637] ? ghes_copy_tofrom_phys+0x70/0x100
> [ 4223.822637] ? __ghes_peek_estatus.isra.16+0x49/0xa0
> [ 4223.822637] intel_pmu_handle_irq+0xba/0x2b0
> [ 4223.822638] perf_event_nmi_handler+0x24/0x40
> [ 4223.822638] nmi_handle+0x4d/0xf0
> [ 4223.822638] default_do_nmi+0x49/0x100
> [ 4223.822638] exc_nmi+0x134/0x180
> [ 4223.822639] end_repeat_nmi+0x16/0x67
> [ 4223.822639] RIP: 0010:qi_submit_sync+0x2c0/0x490
> [ 4223.822639] Code: 48 be 00 00 00 00 00 08 00 00 49 85 74 24 20 0f 95 c1 48 8b
> 57 10 83 c1 04 83 3c 1a 03 0f 84 a2 01 00 00 49 8b 04 24 8b 70 34 <40> f6 c6 10
> 74 17 49 8b 04 24 8b 80 80 00 00 00 89 c2 d3 fa 41 39
> [ 4223.822640] RSP: 0018:ffffc4f074f0bbb8 EFLAGS: 00000093
> [ 4223.822640] RAX: ffffc4f040059000 RBX: 0000000000000014 RCX: 0000000000000005
> [ 4223.822640] RDX: ffff9f3841315800 RSI: 0000000000000000 RDI: ffff9f38401a8340
> [ 4223.822641] RBP: ffff9f38401a8340 R08: ffffc4f074f0bc00 R09: 0000000000000000
> [ 4223.822641] R10: 0000000000000010 R11: 0000000000000018 R12: ffff9f384005e200
> [ 4223.822641] R13: 0000000000000004 R14: 0000000000000046 R15: 0000000000000004
> [ 4223.822641] ? qi_submit_sync+0x2c0/0x490
> [ 4223.822642] ? qi_submit_sync+0x2c0/0x490
> [ 4223.822642] </NMI>
> [ 4223.822642] qi_flush_dev_iotlb+0xb1/0xd0
> [ 4223.822642] __dmar_remove_one_dev_info+0x224/0x250
> [ 4223.822643] dmar_remove_one_dev_info+0x3e/0x50
> [ 4223.822643] intel_iommu_release_device+0x1f/0x30
> [ 4223.822643] iommu_release_device+0x33/0x60
> [ 4223.822643] iommu_bus_notifier+0x7f/0x90
> [ 4223.822644] blocking_notifier_call_chain+0x60/0x90
> [ 4223.822644] device_del+0x2e5/0x420
> [ 4223.822644] pci_remove_bus_device+0x70/0x110
> [ 4223.822644] pciehp_unconfigure_device+0x7c/0x130
> [ 4223.822644] pciehp_disable_slot+0x6b/0x100
> [ 4223.822645] pciehp_handle_presence_or_link_change+0xd8/0x320
> [ 4223.822645] pciehp_ist+0x176/0x180
> [ 4223.822645] ? irq_finalize_oneshot.part.50+0x110/0x110
> [ 4223.822645] irq_thread_fn+0x19/0x50
> [ 4223.822646] irq_thread+0x104/0x190
> [ 4223.822646] ? irq_forced_thread_fn+0x90/0x90
> [ 4223.822646] ? irq_thread_check_affinity+0xe0/0xe0
> [ 4223.822646] kthread+0x114/0x130
> [ 4223.822647] ? __kthread_cancel_work+0x40/0x40
> [ 4223.822647] ret_from_fork+0x1f/0x30
> [ 4223.822647] Kernel Offset: 0x6400000 from 0xffffffff81000000 (relocation
> range: 0xffffffff80000000-0xffffffffbfffffff)
>
> Furthermore even an in-process safe removal unplugged device could be
> surprise removed anytime, thus need to check the ATS Invalidation target
> device state to see if it is gone, and don't wait for the completion/
> timeout blindly, thus avoid the up to 1min+50% (see Implementation Note
> in PCIe spec r6.1 sec 10.3.1) waiting and cause hard lockup or system
> hang.
>
> Signed-off-by: Ethan Zhao <haifeng.zhao@linux.intel.com>
> ---
> drivers/iommu/intel/dmar.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 3d661f2b7946..0a8d628a42ee 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -1423,6 +1423,14 @@ int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
> writel(qi->free_head << shift, iommu->reg + DMAR_IQT_REG);
>
> while (qi->desc_status[wait_index] != QI_DONE) {
> + /*
> + * if the device-TLB invalidation target device is gone, don't
> + * wait anymore, it might take up to 1min+50%, causes system
> + * hang. (see Implementation Note in PCIe spec r6.1 sec 10.3.1)
> + */
> + if ((type == QI_DIOTLB_TYPE || type == QI_DEIOTLB_TYPE) && pdev)
> + if (!pci_device_is_present(pdev))
> + break;
> /*
> * We will leave the interrupts disabled, to prevent interrupt
> * context to queue another cmd while a cmd is already submitted

How about handing this in qi_check_fault() when it detects an ITE error?

qi_check_fault() should returns -ETIMEDOUT instead of -EAGAIN, if

- qi_submit_sync() is called for a device TLB invalidation request
(indicated by pdev is valid);
- device is not present.

Best regards,
baolu